Knowledge that Transforms

When two shapes that differ in orientation or size have to be compared or objects have to be recognized from different viewpoints, the response time and error rate are systematically affected by the size of the geometric difference In this report, we argue that these effects are not necessarily solid evidence for the use of mental transformations and against the use of invariants by the visual system We report an experiment in which observers were asked to give affine-invariant coordinates of a point located in an affine frame defined by three other points The angle subtended by the coordinate axes and the ratio of the lengths of their unit vectors systematically affected the measurement errors This finding demonstrates that the visual system's measurement of invariants need not itself be invariant

This reply to Abelson (this issue) and Petty, Fabrigar, Wegener, and Priester (this issue) is couched within the framework of five basic principles advising that we (1) hang on to what we predicted long enough to test it (Tarzan's leap), (2) be wary of beguiling statistical designs that may not address the question of interest (the Sirens' song), (3) not allow well-worn habits of thinking to ensnare our perceptions (Lavoisier's crease), (4) weigh the possibility of more than one correct hypothesis (the dayyan's decree), and (5) not confuse unplanned with planned contrasts (the archer's aim)

Many researchers have noted the similarities between causal judgment in humans and Pavlovian conditioning in animals One recently noted discrepancy between these two forms of learning is the absence of backward blocking in animals, in contrast with its occurrence in human causality judgment Here we report two experiments that investigated the role of biological significance in backward blocking as a potential explanation of this discrepancy With rats as subjects, we used sensory preconditioning and second-order conditioning procedures, which allowed the to-be-blocked cue to retain low biological significance during training for some animals, but not for others Backward blocking was observed only when the target cue was of low biological significance during training These results suggest that the apparent discrepancy between human causal judgment and animal Pavlovian conditioning arises not because of a species difference, but because human causality studies ordinarily use stimuli of low biological significance, whereas animal Pavlovian studies ordinarily use stimuli of high biological significance, which are apparently protected against cue competition

Chess has long served as an important standard task environment for research on human memory and problem-solving abilities and processes In this article, we report evidence on the relative importance of recognition processes and planning (look-ahead) processes in very high level expert performance in chess The data show that the rated skill of a top-level grand master is only slightly lower when he is playing simultaneously against a half-dozen grand-master opponents than under tournament conditions that allow much more time for each move As simultaneous play allows little time for look-ahead processes, the data indicate that recognition, based on superior chess knowledge, plays a much larger part in high-level skill in this task than does planning by looking ahead

Two experiments tested a form of automatic stereo-typing Subjects saw primes related to gender (e g, mother, father, nurse, doctor) or neutral with respect to gender (e g, parent, student, person) followed by target pronouns (stimulus onset asynchronv = 300 ms) that were gender related (e g, she, he) or neutral (it, me) or followed by nonpronouns (do, all, Experiment 2 only) In Experiment 1, subjects judged whether each pronoun was male or female Automatic gender beliefs (stereotypes) were observed in faster responses to pronouns consistent than inconsistent with the gender component of the prime regardless of subjects' awareness of the prime-target relation, and independently of subjects explicit beliefs about gender stereotypes and language reform In Experiment 2, automatic stereotyping was obtained even though a gender-irrelevant judgment task (pronoun/not pronoun) was used Together, these experiments demonstrate that gender information imparted by words can automatically influence judgment, although the strength of such effects may be moderated by judgment task and prime type